This invention relates to an X - Y plotter, and more particularly to an X - Y plotter of the type which moves a recording paper without perforations in recording.
An example of an X - Y plotter of this type is disclosed in, for example, U.S. Pat. No. Re. 31,684. This kind of X - Y plotter is advantageous in that perforations are unnecessary to be formed in the recording paper, that a simple drive mechanism for moving paper with a small mass enables high-speed recording, that the plotter is small-sized, and so forth.
One of the most important technical problems in this plotter having various advantages is its paper feed mechanism. That is, since no perforations are provided in the recording paper, it is necessary to give a careful consideration for exactly moving the paper without slipping when the feeding of the same.
The plotter disclosed in U.S. Pat. No. Re. 31,684 moves a recording paper by virtue of the friction force between drive rollers each having a knurled surface and pinch rollers. These knurls formed by knurling are, however, comparatively smooth and it is difficult to form projections having sharp tops by the knurling.
Therefore slippage sometimes occurs between the recording paper and the drive rollers, thereby impeding exact feeding.